Pressure responsive measuring instrument



Oct. 1, 1946. A. J. RosENBERGl-:R

PRESSURE RESPONSIVE MEASURING INSTRUMENT .Original Filed Sept. 13, 1940www @atent'ed Oct. l, 1946 PRESSURE RESPONSIVE MEASURING INSTRUMENTAlbert J. Rosenberger,v Chicago, lllsassignor to Republic Flow MetersCompany, Chicago, IIL', a corporation of Illinois l Continuation ofapplication Serial No. 356,601,

September 13, 1940. This 1943, Serial No. 489,130

This invention relates to sensitive instruments and more particularly toinstruments for measuring variations in various physical conditions suchas flow of fluid through a conduit.

In sensitive instruments of this type as heretofore used, andparticularly in fluid owmeters. a body of mercury has generally beenemployed displaced by the action of a pressure or a pressuredifferential. In some cases the use of mercury isundesirable by reasonof its cost, its Weight and the bulk of the instrument required tohandle it and further because it cannot be used with fluids which have achemical reaction with mercury. It is accordingly one of theobjects ofthe invention to provide a sensitive instrument in 'which the use ofmercury or like sealing liquid is eliminated.

Another object of the invention is to provide a sensitive instrumentwhich operates purely mechanically and in which a high degree ofaccuracy can be obtained through an extremely simple construction. 1

Still another object of the invention is to provide a simple mechanicalinstrument in which direct indications on a uniformly graduated scaleare obtained.

The above and other objects, advantages and novel features of theinvention will be apparent vfrom the following description when read inconnection with the accompanying drawing, in which the single figure isa diagrammatic view with parts in section of a fluid flowmeter embodyingthe invention.

The illustrated instrument is adapted to measure and indicate the rateof flow of fluid through a pipe I0 having an orifice plate I2 therein.The instrument is housed in a casing I4 in which is mounted a flexiblediaphragm I6 connected on its opposite sides by pipes I8 to the pipe I0on the opposite sides of the orifice plate I2.

The diaphragm I6 is secured between a bottom housing part 26 secured tothe casing I4 and a top hollow, housing part 22 having an upwardlyextending tubular neck 24 bent ,at right angles to form a horizontaltubular extension 26. The tubular extension 26 supports adjacent itsopen end a bearing 28 on which a weigh beam 30 is pivoted with one endprojecting into the tubular extension 26.

The diaphragm I6 is connected to the end of the weigh beam 30 by a rod32 connected to the diaphragm and having a slot or hole in its upper endslidably receiving an enlarged knob on the end of the beam. A flexibleseal is provided between the beam and extension 26 by a corrugatedflexible tube 34 secured at one end to the open application May 31,

6 Claims. (Cl. 'I3- 407) end of the extension and at its opposite end toa flange or collar on the beam within the extension. This constructionnot only provides a fluid tight seal around the beam but also eliminatesfriction so that sensitivity of the instrument is not interfered with.The seal and bearing construction are preferably constructed foradjustment in accordance with my Patent No. 2,299,179.

At its opposite end the beam 30 carries a valve member 36 movable towardand away from a bleed orifice 38 carried by a hollow block 40 in thecasing. Fluid such as air under pressure is supplied to one end of theblock through a'pipe 42 and flows through a restriction 44 into achamber which communicates with the orice 38 and with a pipe 46. Bymoving the valve member 36 toward and away from the orifice the pressurein pipe 46 will be varied as is understood in the art.

The pipe 46 communicates with the upper part of a hollow casing 48divided by a flexible diaphragm 50 which is urged upward by a spring62.4

The diaphragm 50 carries a rod 64 pivoted to one end of a lever 56 whichis pivoted on a bearing 58. A pointer secured to the lever 56 adjacentthe bearing 58 is movable over a scale 62 to indicate the rate of flow.

The lever 56 forms a part of a square root mechanism connecting thediaphragm 50 to the weigh beam and to this end carries a roller 64`engaging the lower side of a lever 66 pivoted on ,the casing at 68 andlying substantially parallel to the beam 30. Under conditions of no flowthe lever 56 lies at right angles to the lever 66 and is swungcounterclockwise by' the diaphragm 50 when there is flow. The lever 66and the beam 30 are connected by a tension spring 10 adjustablyconnected to the beam byl a screw I2 and which may, if desired, bepretensioned by a weight 14 on the beam 30.

When fluid is flowing through the pipe l0 a pressure differential iscreated across the diaphragm I6 tending to raise it and to swing thebeam 30 counterclockwise. This moves valve member 36 toward the orifice38, raising the pressure in the pipe 46 and above the diaphragm 50. Thediaphragm 50 is moved down against spring 52 by the pressure increaserocking. lever 56 counterclockwise to move the pointer 60 across thescale 62 and to swing the roller 64 to the right and up. The rollerraises the left end oi! Iever 66 swinging it about its pivot 68 andtensioning spring 10 an amount suilicient to create a force on the beambalancing the force exerted by the diaphragm I6.

In operation, the roller 64 will move in an arc and will give to thelever 68 a versine movement modified by the angular eifect of the leverand the varying distance between the pivot B8 and roller B4, Thus themovement of the lever 5B will approximate the square root of thedifferential across the diaphragm i6 throughout the operating range. Ihave found that with a ratio ci about tc 1 between the lengths of levers66 and y56 the accuracy over an angular movement of 45 is Within threetenths of one percent. Since the spring .1D has a linear characteristic,the movement of the diaphragm 50 will be approximately equal tothesquare root of the differential across the diaphragm I6 so that thescale l62 can be uniformly calibrated directly in terms of flow throughthe conduit l0. Also since the motion of the beam is very small andsince it is always returned to substantially the 'same normal position,its control can be effected by a balance of the forces exerted bydiaphragm i6 and spring 10 and its change of position will not affectthe accuracy of the square root mechanism solthat no carefully shapedpositioning cams are required and inaccuracies due to mechanicalimperfections are minimized.

It will be understood that by varying the proportions and relativeangles and lengths of the linkage slightly functions other than thesquare root of the controlling force could be used. Also While theinvention has been shown and described in connection with a fiowmeter itcan equally well be used in the measurement of other conditions and theparticular instrument illustrated is not intended as a definition of thescope of the invention, reference being had for this purpose to theappended claims. Y

This application is a continuation of my copending application SerialNo. 356,601 filed September 13, 1940.

What is claimed is:

1. A sensitive instrument comprising a pivoted beam, means responsive toa condition to be measured for creating a force acting on the beam toswing it in one direction, a pressure control device operated bymovement of the beam for producing a pressure variable with movement ofthe beam, power means operated by the pressure a pressure variable withmovement of the beam, a fluid motor connected to the control device tomove in response to variations in the pressure. a pivoted arm connectedto the motor to be moved about its pivot by the motor, a pivoted levernormally lying substantially at a right angle to the arm with asubstantially straight portion thereof adjacent its free end, means onthe arm at a point adjacent the free end of the arm slidably to engagethe straight portion of the lever and move it an amount proportional todisplacement of said point in a direction at right angles to the leveras the arm is moved, and a spring connecting the lever to the beam tobalance the force of the first named means acting on the beam.

4. A pressure sensitive instrument comprising a pivoted beam, meansresponsive to a condition to be measured for creating a force acting onthe beam to urge it in one direction, a pressure control device operatedby the beam for producing a pressure variable with movement of the beam,a fluid motor connected to the control device to move in response tovariations in the pressure, a pivoted arm connected to the motor to bemoved about its pivot by the motor, a lever pivoted at one end and lyingsubstantially parallel to the beam, means on the arm adjacent the freeend of the arm slidably engaging a substantially straight surface of thelever adjacent the free end of the lever to move it about its pivotdirectly by the arm an amount proportional to displacement of said lastnamed means in a direction at right angles to the lever toward and awayfrom the beam as the arm is moved by the motor, and a tension springconnecting the lever and the beam.

a pressure variable with movement of the beam,

and'movable in response to variations therein, al

pivoted lever lying substantially parallel to the beam, a springconnecting the beam and lever, a pivoted arm lying substantially atright angles to the beam and lever and connected to the power means tobe moved thereby, and a roller carried by the free end of the arm andslidably engaging the lever adjacent its free end to move the lever anamount substantially proportional to the square of the movement of thearm.

2. In a sensitive instrument including a pivoted control beam, a squareroot mechanism cornprising a pivoted lever lying substantially parallelto the beam, a tension spring connecting the lever and beam, a pivotedarm normally lying substantially at a right angle to the lever, means tomove the arm in a direction to move its free end toward the pivot of thelever, and a roller carried by the free end of the arm and engaging thelever adjacent its free end to move the lever an amount substantiallyequal to the square of the movement of the arm.

3. A pressure sensitive instrument comprising a pivoted beam, meansresponsive to a condition to be measured for creating a force acting onthe beam to urge it in one direction, a pressure control device operatedby the beam for producing a fluid motor connected to the control deviceto move in response to variations in the pressure, a pivoted armconnected to the motor to be moved about its pivot, by the motor, alever pivoted at one end and lying substantially parallel to the beam,the arm normally lying substantially at a right angle to the lever witha point adjacent its free end engaging a substantially straight surfaceof the lever adjacent the free end of the lever and movable toward thelever pivot upon an increase in pressure supplied to the motor to movethe lever about its pivot an amount proportional to displacement of saidpoint at right angles to the lever modified by the variation ineffective length of the lever, and a tension spring connecting the leverto the beam.

6. In a sensitive instrument including a pivoted control beam, a squareroot mechanism comprising a pivoted lever lying substantially parallelto the beam, a tension spring connecting the lever and beam, a pivotedarm normally lying substantially at a right angle to the lever with apoint adjacent its free end engaging a substantially straight surface ofthe lever adjacent the free end of the lever to move the lever about itspivot an amount proportional to displacement of said point at rightangles to the lever modified by the variation in effective length of thelever, and means to move the arm about its pivot whereby the arm willmove the lever an'amount substantially equal to the square of themovement of the arm.

ALBERT J. ROSENBERGER.

